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Evolution of catheter-based structural interventions has given patients less invasive alternatives to surgery; however, the current generation of transcatheter heart valves (THV) are not specifically designed for mitral position implantation and have intrinsic geometry that may make mitral implantation suboptimal. Operators are faced with unique challenges with valve deliverability, embolism, and notably left ventricular outflow tract (LVOT) obstruction. Therefore, understanding the suitability of prosthesis delivery and implantation individualized to each heart is of paramount importance.

The blood volume of the mid-to-late systolic phase demonstrating the smallest LVOT surface area between the basal anteroseptal wall of the LV and the most inferior/ventricular hinge of the anterior mitral leaflet or surgical frame strut is segmented out for 3D modeling. CAD models are generated with the proposed THV deployed in different LV landing zones (60% LV/40% atrial to 80% LV/20% atrial) within the patient’s MA/ring (A). In the setting of surgical bioprosthesis, modeling is performed with 0% defined within the confines of the inferior border of the surgical prosthesis strut, and 10% as inferior to the surgical prosthesis plane into the LV. The post-TMVR residual LVOT, “neo-LVOT,” surface area is then calculated for proposed THV by various depths of LV deployment and angulations of THV delivery system toward/away from aortic outflow tract (B and C). In order to predict percentage of LVOT obstruction, the ratio of neo-LVOT to native LVOT surface area is calculated: (native LVOT area – neo LVOT area)/native LVOT area. Abbreviations as in Figure 1.

CT, Computer-Aided-Design, and 3D Print Analysis of the LVOT to Characterize and Quantify the Residual Post-TMVR “Neo-LVOT” Area Overcomes the Limitations of Traditional 2D Imaging Planes

Preliminary data utilizing 2-dimensional (2D) echo imaging correlated acute angulation of the mitral aorta-outflow-angle (mAOA) with higher risk of LVOT obstruction compared with that of more obtuse mAOA. On the basis of our single-center experience, the association between mAOA and risk of LVOT obstruction was not reproducible (A and B). LVOT obstruction is not solely dependent on mAOA. Personalization and determination of feasibility of TMVR in patient-specific anatomy may not be accounted for if relying on 2D measurements of a 3D anatomy (A). CT and CAD 3DP analysis of the “neo-LVOT” surface area overcomes the limitations of traditional 2D imaging planes. THV implantation in the mitral position results in permanent anterior motion/displacement of the surgical/native anterior mitral leaflet. Both THV frame and permanent anterior motion/displacement can result in severe LVOT obstruction (C). The importance of understanding the application of this technology is the ability to test devices in patient-specific cardiac anatomy ex vivo for LVOT encroachment. Abbreviations as in Figure 1.

Acknowledgments

Footnotes

Drs. Wang, O’Neill, Mr. Myers, and Mr. Forbes are co-inventors on a patent application, assigned to their employer Henry Ford Health System, on software to predict LVOTO. Dr. Greenbaum is a proctor for Edwards Lifesciences and St. Jude Medical. Dr. Guerrero has received a research grant from and is a proctor for Edwards Lifesciences. Dr. Paone is a consultant and proctor for Edwards Lifesciences. Dr. O’Neill is a consultant for Edwards Lifesciences, Medtronic, and St. Jude Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.